1. Field of the Invention (Technical Field)
The present invention relates to apparatus and methods for irrigation, particularly residential and commercial landscape irrigation, and specifically to an irrigation system and apparatus which is readily adaptable to varying circumstances and which promotes uniform and manageable irrigation water pressure.
2. Background Art
The inconvenience of moving and situating traditional lawn and garden watering hoses, coupled with their unsightliness and inefficiency, has increased the popularity of permanently installed sub-surface residential and commercial landscape irrigation systems. In the typical installation, the overall system is connected to a single source of water, commonly a public water line at or near the residential or commercial structure. The system normally features some type of back-flow preventer at the interface between the irrigation system and the source, to prevent the backflow of irrigation water into the potable public supply. A master valve preferably, but not always, is installed near the backflow preventer to provide a means for shutting off the water supply to the entire irrigation system. Downstream from the master valve a manifold system is usually provided, consisting of two or more control valves. The manifold divides the main delivery line into two or more zone lines, so that the control valves and zone lines may be used to selectively deliver water to defined "zones" of the landscape. Accordingly, the typical irrigation system currently consists of a number of "forks" or branch lines depending from a single manifold at or near the master source. In some sophisticated systems zone lines may form a circuitous loop. Much more frequently, each zone line is a non-circuitous "dead end" wherein all the water entering the line must be expelled through the dischargers (e.g. sprinklers, bubble irrigators, and the like) on the line; no water returns to the manifold from the zone line.
In this specification and in the claims, "line" shall generally mean a tubular means for conveying a liquid, including pipelines for carrying irrigation water, regardless of material composition or pipeline diameter, unless otherwise specified. In the preferred embodiment of the invention, a line is a flexible tubular pipeline for conveying water beneath the surface of the ground.
The conventional system is problematic in at least two regards. First, the standard system suffers from reduced hydraulic efficiency due to the multi-branched system layout. In the standard ramified layout, each and every branch or "zone" line originates at the manifold (near the master source) and extends--often a considerable distance--to the sometimes remote area of discharge. The extended length of each zone line impairs the delivery of water therethrough. The numerous dead-end branch lines commonly have seriously non-uniform pressure along their respective lengths. Pressure in a given branch line commonly is comparatively high near the manifold (where pressure is nearly equal to the pressure in the main), but falls off considerably as a function of the distance away from the source and toward the distal end of the line. The cause of such a drop-off in pressure is known in the art of fluid mechanics, and is a function of, among other things, the line material and line inside diameter, as well as the length of the line. Nevertheless, the largely intuitive appeal of ramified, "zone" layouts continues to induce their adoption by landscape and irrigation system designers. This popularity continues despite the fact that overall system function is impaired by the reduced water pressure at remote and distally located points of discharge along a branch line. Because pressure varies along the line, identical sprinkler heads manifest inconsistent performance at different points along the line, making deliberate design for uniform and adequate irrigation difficult, particularly for large or irregularly-shaped lawns.
A related drawback of conventional systems is that they are difficult or impossible to expand or customize to meet changing landscaping designs or irrigation needs. For example, to modify an extant system to irrigate a later-added flower garden, an entirely new zone line must be installed, running from the manifold to the zone of the new flower garden. Such an installation requires that the existing landscape be disturbed along a line from the manifold to the flower garden, at significant cost and disruption. The additional line may be especially difficult or disruptive if the new flower garden is distantly located, or if imposing or valuable landscape features (concrete driveways, established flower beds, or the like) have been placed in intervening locations. Moreover, existing branch lines normally may not be tapped into or extended to meet the new demand of the added flower garden. Existing lines usually will be "fine-tuned," for example using particular sprinkler heads at particular locations, to meet only the needs of their respective existing zone. Tapping into or extending extant lines upsets the previous engineering design for that zone, usually resulting in the under-irrigation of the zone during operation of the system.
The adaptability and installation of many known types of irrigation systems also often is complicated by the complex pipe-and-joint mode of construction. Many subsurface systems are constructed of polyvinyl chloride (PVC) pipe, which is comparatively rigid. PVC systems thus must be assembled using a wide assortment of fittings to provide for elbows, tees, forks, bends, and the like. The fitted connections are performed using chemical primers and solvents to bond the fittings together, a labor-intensive process that can be slow and fraught with a number of complications, particularly with inexperienced labor.
Some efforts have been made to avoid the difficulties associated with PVC pipe systems by constructing systems of flexible plastic lines. Such systems have not enjoyed as widespread a popularity as might be expected due, among other reasons, to the perceived need usually to provide a clamped compression at joints and fittings to avoid unacceptable leakage.
Patents representing previous efforts to provide improved tools for irrigation system installation include, for example, U.S. Pat. No. 5,226,231 to De Leebeeck, and U.S. Pat. No. 4,054,984 to Ball et al. Also, a number of disclosures are directed to fittings, couplers, and methods of joining pipe lines, including U.S. Pat. No. 5,484,174 to Gotoh, et al., U.S. Pat. No. 5,395,139 to Morrisson, U.S. Pat. No. 5,251,938 to Ericksen, U.S. Pat. No. 5,242,112 to Dunn et al, U.S. Pat. No. 5,039,011 to Parker, U.S. Pat. No. 4,971,366 to Towsley, U.S. Pat. No. 4,712,811 to Wier, U.S. Pat. No. 4,045,060 to Daigle, U.S. Pat. No. 3,973,732 to Diggs, and U.S. Pat. No. 3,957,292 to Diggs.
A need remains, nevertheless, for an irrigation system and apparatus which promotes uniform water pressure at all points in the system, and which is readily customized and adapted to meet altered landscape designs or modified irrigation needs without upsetting preexisting installation and performance design. A desirable such system also should be easy to install without labor-intensive or time-consuming fittings. From this background, the present invention was developed.